JPS6399123A - Reamer - Google Patents

Abstract

PURPOSE:To make is possible to prevent a drill section from being broken, by forming cutting edges formed in grooves and chisel cutting edges formed in a thick core part by thinning in straight line-like shapes, respectively, and by setting the angle of the cutting edge to a value less than a predetermined angle. CONSTITUTION:Cutting edges 4 formed in grooves 3 are formed in a straight-line L shape so as to extend from a point P0 on the outermost periphery to the center axis O, and the centriperal angle alpha of the cutting edges 4 which respect to the straight- line L is set within a range of + or -5 deg.. Further, chisel cutting edges 7 formed by parts 6 which are ground off by thinning are formed in a straight line-like shape, extending from a point Pi on the innermost periphery to the center axis O with the axial rake angle theta thereof being set within a range of + or -5 deg.. Further, the diameter C of the thick core part 1 is set within a range of 0.25-0.4 times large as the diameter D of the drill part, and a remaining core part which is formed when a chisel point 8 is left without being ground during thinning, is set within a range of 0-0.1 times as large as the diameter D of the drill part. Thus, it is possible to obtain a strength sufficient for preventing the drill part from being broken, and to facilitate the regrinding process.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a reamer having a drill portion, and particularly to a reamer in which the cutting edge of the drill portion has a cutting edge shape that facilitates re-grinding.

[Prior art]

In conventional drilling, a pilot hole is drilled using a drill, and then finishing is performed using a reamer. However, since two types of tools, a drill and a reamer, are used in this process, there are problems in that the working time is long and the tool cost is also high. As a solution to this problem, as shown in Figure 5,
A reamer 11 has been developed in which a drill part 5 for drilling the pilot hole and a reamer part 10 for finishing the hole are integrated. According to this reamer 11, the above-mentioned two types of machining can be performed with one tool, thereby reducing machining time and tool costs.

[Problems to be solved by the invention]

By the way, cutting tools generally have the problem of cutting damage and chipping of the cutting edge, which occur based on the relative relationship between the rigidity and brittleness of the material and the cutting resistance. As mentioned above-
In the reamer, chipping of the cutting edge of the drill section 5 impairs the precision of the prepared hole, and in turn affects the precision of finishing by the reamer section 10. For example, regarding drills, in Japanese Patent Publication No. 61-30845 and Japanese Patent Publication No. 58-18163, in order to reduce cutting resistance and prevent chipping of the cutting edge,
: A technology has been disclosed in which the direct view shape of the j and i planes is formed using specific curves, but even with drills whose cutting edges are formed according to these curves, the lifespan of the drills varies widely, and the main cause of this is chipping. It is thought that there is. One of the causes of this chipping is that the cutting edge is curved, and when the cutting edge is curved, it is difficult to perform honing, which is the process of applying a minute chamfer to the cutting edge. The honing process was done manually using a tool called a drapper, but if the cutting edge is curved, the accuracy of the finished product is highly dependent on the skill level of the operator, and as a result, the accuracy of the finished product is scattering"
is occurring. Therefore, cutting performance is not stable, and it is also a cause of "variation" in life. Particularly in the case of trills, if chipping occurs on the cutting edge, it is re-grinded and reused, but finishing the cutting edge into a precise curved shape requires extremely advanced technology. In particular, if the cutting edge at the center, that is, the diesel blade, is formed into a curved shape, edge grinding is difficult, and a special dedicated machine tool is required. Ma f2, d continuously on the zizel blade and its outer circumference side? Since the shape of the continuous part with the cutting edge that extends to the part does not change smoothly, the cutting force is concentrated in this part and depping is likely to occur. The present invention has been devised in view of the above problems and to effectively solve them. Therefore, the purpose of this tool is to provide sufficient strength to prevent the drill part from breaking and to provide sufficient sharpness to the cutting edge of the drill part, whether it is made of general tool steel or cemented carbide. Another object of the present invention is to provide a reamer with high finishing accuracy, which is equipped with a drill portion having a cutting edge shape that allows easy honing and re-grinding of the cutting edge and prevents depping.

[Means to solve the problem]

The reamer according to the present invention has the following configuration in order to solve the problems of the prior art and achieve the purpose. That is, in a reamer in which a drill part is formed at the tip of the reamer part, with respect to the shape of the cutting edge formed on the axial end face of the drill part when viewed directly from the end surface, the cutting edge formed in the groove part,
Diesel blades formed by thinning in the thick core portion are each formed in a straight line. The angle formed by the straight line of the cutting blade with respect to the straight line passing through the outermost point of the cutting blade and the axis of the drill part is -5° or more and +5° or less in the rotational direction of the reamer. The diameter of the thick core part is 0.25 times or more the diameter of the drill part"-0
, is 4 times or less. The chisel blade has an axial angle of 15° or more and +5° or less, and its tip center remaining dimension is 0 times or more and 0.1 times or less of the drill diameter. Although the reamer is sufficiently effective in general tool steel reamers, it is particularly effective when the reamer is made of cemented carbide as a technique for overcoming the brittleness of that material.

[Function] The drill according to the present invention functions as follows in order to solve the problems of the prior art and achieve the purpose. That is, regarding the shape of the cutting edge formed on the axial end surface of the drill portion when viewed directly from the end surface, the cutting edge formed in the groove portion and the diesel edge formed in the thick core portion by thinning are each formed in a straight line. Therefore, honing and re-grinding of the cutting edge can be performed by simply moving the tool linearly, and the cutting resistance is not concentrated in one place but is distributed approximately evenly over the entire cutting edge. The angle formed by the straight line of the cutting blade with the straight line passing through the outermost point of the cutting blade and the axis of the drill part is -5° in the rotation direction of the reamer.
By setting the angle to +5° or less, the rake angle in the radial direction of the cutting blade is suppressed within a predetermined range, so the cutting resistance is also suppressed to a small level, and sufficient sharpness of the cutting blade is ensured. The diameter of the thick core part is 0.25 times or more the diameter of the drill part.
Since it is sufficiently large (less than 4 times), the bending and torsional rigidity of the drill part is increased, and it prevents breakage especially when manufactured from brittle materials such as cemented carbide, and allows heavy cutting. Close. By setting the axial rake angle of the diesel blade to 15 degrees or more and +5 degrees or less, the sharpness of the diesel blade is ensured without impairing its strength. In addition, by forming a centering portion with a tip centering dimension of 0 times to 0.1 times the diameter of the drill part, the required strength of the chisel blade tip, that is, the crushing of the chisel point can be prevented depending on the cutting conditions. Strength is ensured, and the biting ability of the drill part is improved to eliminate the walking phenomenon of the tip and to eliminate misalignment of the center of the drill. In other words, since the drill part can accurately drill a hole at a predetermined position, when the reamer part cuts the inner circumferential surface of the prepared hole, each cutting edge of the reamer part can cut in a well-balanced manner. , the finishing accuracy of the reamer section is improved. [Example] A preferred embodiment of the present invention will be described below with reference to Figures 1 to 4.
This will be explained with reference to the figures. FIG. 1 is a plan view showing the cutting edge of the drill portion of the reamer according to the present invention, viewed directly from the end surface side. In the figure, 1 is a core thick part, 2 is a land part, and 3 is a groove part. 'f
! The straight line or curve of the cutting edge 4 formed in the section 3 is determined by the diameter, helix angle, core thickness, and tip angle of the drill section 5.
is formed in a straight line from the outermost point Po toward the axis O of the drill 5. That is, the cutting edge 4 is
If the angle α between the straight line and the rotational direction of the reamer 11 (indicated by arrow A in the figure) is defined as concentricity, then in this embodiment, concentricity is set to 0°. However, the lamer of the present invention is not limited to this, and as shown in FIG. 2 or 3, the concentricity of the cutting edge 4 of the drill portion 5 is set within a range of ±5°. That's fine. A portion 6 shown by smudging is a portion shaved off by thinning, and 7 is a chisel blade formed by this thinning. This diesel blade 7 is also formed in a straight line from a point Pi at the innermost peripheral end of the cutting blade 4 toward the axis O. The diameter dimension C of the core thick part I is set within a range of 0.25 times or more and 0.4 times or less of the diameter of the drill part. FIG. 4 is a sectional view taken along the line IV-IV in FIG.
The rake angle θ of the chisel blade 7 in the axial direction is set within a range of -5° or more and +5° or less. In the embodiments shown in FIGS. IF to 3, the dimension of the centering part formed by leaving the chisel point part 8 uncut during thinning is 0, but crushing of the chisel point part 8 can be prevented depending on the cutting conditions. In order to provide rigidity, the center portion may be formed within a range of 0 times or more and 0.1 times or less the diameter of the drill portion. Note that the straight cutting edge 4 is point symmetrical with respect to the axis O of the drill part 5.
, 7 are easily broken due to the large circumferential speed difference between the chips cut out at the outer circumference and the chips cut out at the inner circumference, improving the evacuation of the chips.

【Effect of the invention】

As is clear from the above description, the present invention provides the following excellent effects. That is, since the cutting edge of the drill portion is formed substantially straight, it is easy to honing it, and "variations" in machining accuracy are reduced, so that the tool life is averaged and there are no tools that have an extremely short life. Also, re-grinding can be done easily.
This can also be done by the user. Furthermore, since there are no locations where chipping is likely to occur, the overall incidence of chipping is lowered and the tool life is extended. Since the core thickness is sufficiently ensured, breakage of the drill part can be sufficiently prevented. In addition, by setting the concentricity of the cutting edge of the drill part within a predetermined range, the rake angle in the radial direction of the cutting edge can also be suppressed within a predetermined range, so cutting resistance can be kept small and the cutting edge can be fully Sharpness is ensured. Since the core thickness is sufficiently ensured, breakage of the drill part can be prevented. The chisel blade has an appropriate axial rake angle, ensuring sharpness without sacrificing strength. Since the tip center remaining portion is formed with the necessary dimensions, the necessary strength of the chisel blade tip is ensured, and furthermore, the biting property of the drill part is improved to eliminate the tip walking phenomenon and center misalignment. In other words, since the drill part can accurately drill a hole at a predetermined position, when the reamer part cuts the inner circumferential surface of the prepared hole, each cutting edge of the reamer part can cut in a well-balanced manner. , the lifting accuracy of the reamer section is improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the cutting edge of the drill portion of an embodiment of the reamer according to the present invention, viewed directly from the end surface side. FIGS. 2 and 3 are plan views showing the cutting edge of the drill portion of another embodiment of the reamer according to the present invention, viewed directly from the end surface side. Figure 4 is the IV of Figure 1.
-I'/It is a sectional view taken along the arrow. FIG. 5 is a front view showing a general schematic configuration of a reamer having a drill portion at the tip of the reamer portion. l... Thick core part, 4... Cutting edge, 5... Drill part, 7
...Chisel blade, 10...Reamer part, C...Diameter of thick core part, D...Drill part diameter, Po...Outermost point of cutting edge, 0...Drill Axis center, L...point PO
and a straight line passing through the axis 0, α...The angle that the straight line of the cutting edge makes in the direction of rotation of the drill with respect to the straight line, 0...The rake angle of the chisel blade in the axial direction.

Claims (1)

[Claims] (1) In a reamer in which a drill part (5) is formed at the tip of the reamer part (10), the drill part (5) has the following features regarding the shape of the cutting edge formed on the axial end face when viewed directly from the end face.
A cutting edge (4) formed in the groove portion and a chisel blade (7) formed in the thick core portion (1) by thinning are each formed in a straight line, and the outermost peripheral end point of the cutting edge (4) is formed in a straight line. (Po) and the straight line (L) passing through the axis (0) of the drill part (5), the angle (α) formed by the straight line of the cutting edge (4) is −5 in the rotational direction of the reamer. The diameter dimension (C) of the thick core portion (1) is at least +5°, and the diameter dimension (C) of the thick core portion (1) is
5), and the chisel blade (7) has an axial rake angle (θ) of -5° or more and +5° or less, and A reamer characterized in that a tip center remaining dimension is 0 times or more and 0.1 times or less of the drill portion diameter (D).